diff --git a/Lib/fontTools/__init__.py b/Lib/fontTools/__init__.py
index 6cc1b1247..893088658 100644
--- a/Lib/fontTools/__init__.py
+++ b/Lib/fontTools/__init__.py
@@ -3,6 +3,6 @@ from fontTools.misc.loggingTools import configLogger
 
 log = logging.getLogger(__name__)
 
-version = __version__ = "4.28.0"
+version = __version__ = "4.28.1.dev0"
 
 __all__ = ["version", "log", "configLogger"]
diff --git a/setup.cfg b/setup.cfg
index 94c7d9257..e8c4960dc 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,5 +1,5 @@
 [bumpversion]
-current_version = 4.28.0
+current_version = 4.28.1.dev0
 commit = True
 tag = False
 tag_name = {new_version}
diff --git a/setup.py b/setup.py
index 82a42ef6a..af23991b4 100755
--- a/setup.py
+++ b/setup.py
@@ -441,7 +441,7 @@ if ext_modules:
 
 setup_params = dict(
 	name="fonttools",
-	version="4.28.0",
+	version="4.28.1.dev0",
 	description="Tools to manipulate font files",
 	author="Just van Rossum",
 	author_email="just@letterror.com",